Re: [PATCH 0/2] Begin auditing SECCOMP_RET_ERRNO return actions

On Mon, Jan 2, 2017 at 11:53 AM, Tyler Hicks <tyhicks(a)canonical.com&gt; wrote: > This patch set creates the basis for auditing information specific to a given > seccomp return action and then starts auditing SECCOMP_RET_ERRNO return > actions. The audit messages for SECCOMP_RET_ERRNO return actions include the > errno value that will be returned to userspace. I'm replying to this patchset posting because it his my inbox first, but my comments here apply to both this patchset and the other seccomp/audit patchset you posted. In my experience, we have two or three problems (the count varies depending on perspective) when it comes to seccomp filter reporting: 1. Inability to log all filter actions. 2. Inability to selectively enable filtering; e.g. devs want noisy logging, users want relative quiet. 3. Consistent behavior with audit enabled and disabled.

My current thinking - forgive me, this has been kicking around in my head for the better part of six months (longer?) and I haven't attempted to code it up - is to create a sysctl knob for a system wide seccomp logging threshold that would be applied to the high 16-bits of *every* triggered action: if the action was at/below the threshold a record would be emitted, otherwise silence. This should resolve problems #1 and #2, and the code should be relatively straightforward and small.

As part of the code above, I expect that all seccomp logging would get routed through a single logging function (sort of like a better implementation of the existing audit_seccomp()) that would check the threshold and trigger the logging if needed. This function could be augmented to check for CONFIG_AUDIT and in the case where audit was not built into the kernel, a simple printk could be used to log the seccomp event; solving problem #3.

We could also add a SECCOMP_RET_AUDIT, or similar, if we still feel that is important (I personally waffle on this), but I think that is independent of the ideas above.